Theoretical study and simulation of moisture transport in unsaturated porous media by periodic homogenization

In this work, the macroscopic Richards equation for moisture transport is established in unsaturated porous media using periodic homogenization. By performing dimensional analysis on microscopic equations of moisture transfer, dimensional numbers characterizing moisture transport appear. The application of the asymptotic homogenization leads to the classical Richards equation, which is justified rigorously this way. Moreover, we obtain an accurate definition of the homogenized diffusion tensor of moisture involving the geometric properties of the microstructure and known transport properties of the material. A different behavior for the transport of water vapor between hygroscopic and super-hygroscopic region is revealed. Finally, a simple 2D example where an analytical solution exists is addressed. Copyright (c) 2014 John Wiley & Sons, Ltd.